In the above-referenced parent patent application, there is disclosed a fan-beam collimator which has a plurality of focal lengths and which is therefore entitled a "multifocal collimator". The collimator there disclosed is a parallel beam collimator as viewed along the axial direction and has its plurality of focal lengths in the transaxial direction. Persons skilled in the art will understand that the term "axial direction" refers to a direction which is parallel to the axis of rotation of the collimator in rotational camera transaxial SPECT (single photon emission computed tomography). "Transaxial direction" means a view taken perpendicular this axis of rotation.
While the collimator described in the above-referenced parent patent application is highly advantageous as compared with known collimators, it would be desirable to further improve upon it while still preserving the improved center sensitivity and the lack of truncation errors and corresponding artifacts.
It is therefore one object of the invention to provide a multifocal collimator which improves upon the above-referenced multifocal fan-beam collimator.
Another object is to provide a scintillation camera system which will improve images of comparatively small body organs, such as the heart.
Another object of the invention is, in general, to improve upon known rotational camera transaxial SPECT scintillation camera systems.